Flash paper is a staple for stage illusionists to create fire tricks and, as long as you follow safety protocols, can be a fun chemistry experiment.

YouTube user Nighthawkinlight demonstrates a method for making Nitrocellulose (aka flash paper) using cotton squares cut from a t-shirt, sulfuric acid (drain cleaner) from a plumbing supply shop, and potassium nitrate. You'll add the potassium nitrate to the sulfuric acid and stir to create nitric acid and pour that over your cotton strips. After letting the cotton soak for an hour you'll neutralize the acid by adding water (usually you only add acid to water but see the video for the explanation why this case is different) and a solution of sodium bicarbonate (baking soda) and water. After drying out the flash paper will briefly flare up with fire when lit by a flame. Many stage magic effects have used nitrocellulose over the years and while there are otherwise no practical applications (maybe to help start a fire in a survival situation) it is a fun chemistry experiment as long as you follow proper safety procedures.

Keep in mind that, because this project involves using acid and acid vapor, you need to make sure you're wearing safety glasses and have water and baking soda nearby in case of accidental contact. Also make sure this is done outside as you don't want the acid vapors in your home.